(1) Field of the Invention
This invention is concerned with machines adapted for in the manufacture of shoes, more especially with machines for operating, e.g. performing a roughing operation, progressively along marginal portions of shoe bottoms and/or for performing a scouring action on end portions of shoe bottoms. The term "shoe" is used herein generically as indicating articles of outer footwear, and as including articles of outer footwear in the course of their manufacture.
(2) Prior Art
In one known machine for performing a roughing operation progressively along marginal portions of a shoe bottom, there are provided a shoe support, for supporting a lasted shoe, bottom uppermost, tool supporting means for supporting two rotary roughing tools in the form of wire brushes, and means for effecting relative movement, lengthwise of the bottom of a shoe supported by the shoe support, between the shoe support and the tool supporting means in one direction along a path, template means being provided, mounted on the shoe support, whereby, as relative lengthwise movement takes place as aforesaid, relative movement, widthwise of the bottom of a shoe supported by the shoe support, is also caused to take place between the shoe support and the tool supporting means, so that the tools supported by the tool supporting means can operate progressively along opposite marginal portions of the shoe bottom. Furthermore, in said machine, the tools are arranged in tandem relationship so that, as relative lengthwise movement takes place as aforesaid, first one tool engages the shoe bottom and operates along one marginal portion, and thereafter, following said one tool, the other tool engages the shoe and operates along the opposite marginal portion, the arrangement being such that the relative lengthwise movement is arrested when said other tool has completed its operation. Thereafter, with the tools in an out-of-the-way condition, relative lengthwise movement may then take place in an opposite direction along said path and the shoe can then be removed from the shoe support.
Whereas the machine referred to above operates satisfactorily on a variety of shoe styles and sizes, nevertheless it will be appreciated that the machine cycle includes a certain amount of "dead" time, in which the shoe bottom is not being operated upon but is merely being returned to a loading position. Furthermore, by arranging the tools in tandem relationship, the amount of relative lengthwise movement necessary for both brushes to traverse their respective marginal portions is greater than the overall length of the shoe, and this in turn leads to an extended machine cycle time.
Furthermore, the brushes always operate on the shoe bottom in the same direction, so that the "leading" edge of the operating surface of each brush is more subject to wear than the "trailing" edge of that surface, with the result that uneven brush wear takes place with consequently shortening of the effective life of the brush.
The use of template means in the aforementioned machine is highly efficient in ensuring that the path of relative movement followed by the roughing tools in relation to the shoe bottom being operated upon is closely controlled so that roughing of the shoe bottom is effected only in the areas intended to be roughed. This is of special importance insofar as any "over-roughing" of the shoe bottom, i.e. roughing beyond the featherline, will be visible in the finished shoe (unless of course the shoe construction requires such "over-roughing", e.g. if the sole unit to be applied extends up the sides of the finished shoe, in which case the machine employing the template means can be so set to control the degree of "over-roughing"). Similarly, "under-roughing" may provide an insufficient area of roughed material to ensure a good bond with the sole unit to be attached; furthermore, "under-roughing" means that the area of rough does not extend up to the featherline, so that gaping may arise in the finished shoe between the attached sole unit and the lasted-over portions of the upper.
Template means do, however, present a problem of storage, especially in cases where one template is provided for each size, or perhaps for two or three half-sizes, of a given style. To overcome this problem, it has been proposed to use a single, adjustable template for each style, but such an arrangement has not proved satisfactory. Furthermore, in other machines for performing a roughing operation progressively along marginal portions of shoe bottoms, in order to avoid the use of template means, it has been proposed to use the edge of the shoe itself for purposes of guiding the tool(s). However, problems may arise in such a case in that, especially in the instep region of the shoe bottom, the edge of the shoe bottom may be insufficiently defined satisfactorily to guide a tool along the shoe bottom marginal portion.
Furthermore, prior to effecting a marginal roughing operation, whether by one or other of the aforementioned machines or whether by hand, it is customary first to remove any significant pleats which have been formed, during the preceding lasting operation, especially at the toe end of the shoe, such removal generally being effected using a rotating toe scouring roll or a toe scouring band to which the shoe bottom is presented manually. At least when using the machine first mentioned above, this manual toe scouring operation can be effected during the marginal roughing machine cycle without significantly affecting the cycle time. However, if the cycle time were to be shortened to any significant extent, then manual toe scouring could no longer be effected.
Again, in the machine first mentioned above means is provided for maintaining the brushes in a sharpened condition, said means including stationary grinding stones contoured to the desired shape of the operating surface of each brush. In using such means, in order that the burrs formed during sharpening will be directed so as to improve the cutting effect of the brush during the roughing operation, it is necessary to reverse the direction of rotation of each brush for the grinding operation. After grinding, of course, the direction of rotation has to be once more reversed back to the "roughing" direction. To this end, clearly a reversible motor has to be used for the rotation of each brush. Furthermore, since grinding takes place relatively frequently (e.g. desirably once every 20 or so machine cycles), the constant starting and stopping of the motor tends to shorten the life of the motor. Again, because of the need to reverse the direction of rotation of each brush twice for each grinding operation, a good deal of operating time is lost for each grinding operation.